A group of cancer experts says research into breast screening confirms that it saves lives - but can only help certain women.

There has been ongoing controversy about whether screening has actually led to a fall in the number of deaths from breast cancer.

However, the International Agency for Research on Cancer (IARC) has examined all the evidence for and against screening - and its overall verdict is that it should continue.

It says that, for every 500 women screened, over a ten year period, one of them will be saved by breast screening.

Each year, thousands of UK women undergo breast mammograms, an x-ray which may reveal if there is a tumour growing in breast tissue.

The UK programme currently offers it to women aged between 50 and 70.

Women have to know that it's not a foolproof method

Professor Valerie Beral, IARC

However, breast screening is not totally without its own slight risks - false alarms can cause anxiety, and, as a result of the tests, women may undergo surgery to remove growths which would have never caused illness.

Some experts have argued that it is possible that these problems might actually outweigh any lives saved by the screening programme.

They say that, for the £50m a year it costs to run it, other treatments and expensive drugs could have been bought.

But the IARC - an offshoot of the World Health Organisation - says that the evidence is clear.

Professor Bruce Armstrong, who chaired the breast screening working group, said: "A quality screening programme - done every two years in women aged 50 to 69 - will reduce the risk of death from breast cancer.

"It would be reasonable for health services to expect a fall in mortality from breast cancer of some 20% in the long term".

Three-quarter success

The group found that, on average, women taking part in such a screening programme could expect a fall of up to 35% in their personal breast cancer risk.

Approximately 1.1m women aged between 50 and 64 were screened last year - 75% of those invited.

The government is currently extending the national programme so that women up to 70 years old are included.

Death rates from breast cancer have indeed been falling in the UK since the inception of the breast screening programme more than a decade ago.

Breast cancer facts

33,000 new cases each year - screening detects 8,300

Lifetime risk of developing cancer: 1 in 9

11,380 deaths in 2000

1.3 million women screened - 1.6m invited

However, the working group did recommend that women should be better informed of the potential risks involved with taking part in screening.

Professor Valerie Beral, another working group member, and a professor of epidemiology at the University of Oxford, said: "Women have to know that it's not a foolproof method - some cases are not visible by mammography, some are just missed, and sometimes new cancers grow in the interval between screenings.

"However, many people buy lottery tickets where the chance of winning is one in a million - if you put to them a one in 500 chance that they will be alive - that's a good chance."

Limited value

The group did find that there was only limited evidence of benefit for breast screening for those in their 40s, or over the age of 70.

Current evidence based on actual screening outcomes strongly supports its effectiveness

Dr Robin Wilson, Nottingham City Hospital

An expert at the European Breast Cancer Conference in Barcelona also backed screening.

Dr Robin Wilson, a consultant radiologist at Nottingham City Hospital, insisted it was effective.

He told the conference: "Whatever the issues are surrounding the claims and counter claims about the validity of the trials and the review, the fact is that we have moved on a long way since the randomised trials that contributed to the review.

Julietta Patnick, the national co-ordinator of the NHS screening programme,
which was set up in 1988, said: "We operate a policy of informed choice but in the context of a national
policy which believes that breast screening has benefits, and we encourage women
to be screened.